Pressure exchanger rotor



Dec. 8, 1970 Filed Jan 14, 1969 D. H. WILLIAMSON PRESSURE EXCHANGER ROTOR 3 Sheets-Sheet 1 @OIGL/IS HERBERT Mu IAMSO/V Arman 315 Dec. 8, 1970 H. WILLIAMSON PRESSURE EXCHANGER ROTOR 3 Sheets-Sheet I Filed Jan. 14, 1969 .Z/vuE/v row 7 o usm s HmBERTh/ILLMM so/v A TTOR/VE 1 5 Dec. 1970 D. H. WILLIAMSON I 3,54

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United States Patent 3,545,882 PRESSURE EXCHANGER ROTOR Douglas Herbert Williamson, Derby, England, assignor to Rolls-Royce Limited, Derby, England Filed Jan. 14, 1969, Ser. No. 791,107 Claims priority, application Great Britain, Jan. 17, 1968, 2,545/ 68 Int. Cl. F01d /22 U.S. Cl. 416-190 Claims ABSTRACT OF THE DISCLOSURE A pressure exchanger rotor has radially spaced apart inner and outer shrouds between which extend a plurality of angularly spaced apart vanes to define therewith pressure exchanger cells, the vanes having shroud portions which collectively constitute at least one of the said shrouds and which slidingly abut each other at all times to accommodate differential thermal expansion between the said shrouds and vanes.

This invention concerns improvements relating to a rotor for a rotary pressure exchanger.

According to the present invention, there is provided a pressure exchanger rotor having inner and outer shrouds which are radially spaced apart, a plurality of angularly spaced apart vanes extending between the shrouds to define therewith a plurality of angularly spaced apart axially extending pressure exchanger cells, each of which is open at its opposite ends, at least the outer shroud consisting of shroud portions which are carried by the vanes, each shroud portion having surfaces at its ends, which surfaces are circumferentially slidable over those of adjacent shroud portions, the shroud portions being in sliding abutment at all times.

The term vanes is used in this specification in a broad sense as including blades.

Thus each of the vanes may have a shroud portion which is connected to the adjacent shroud portions by tongue and groove connections.

In another form of the present invention, each shroud portion has sloping end surfaces which are radially and circumferentially slidable over those of the adjacent shroud portions.

The inner shroud may also consist of shroud portions which are carried by vthe vanes, each shroud portion having sloping surfaces at its ends, which surfaces are radially and circumferentially slidable over those of adjacent shroud portions, the shroud portions being in sliding abutment at all times.

Preferably the centre of gravity of each shroud portion is circumferentially offset with respect to that of its vane so that, when the rotor is rotated, the sloping end surfaces of adjacent shroud portions are forced against each other by centrifugal force.

Preferably, the peripheral length of the outer shroud portion carried by each vane is approximatel the same as the radial length of the vane.

The construction is preferably such that, when the rotor is cold, the shroud portions are in interference fitting engagement with each other.

A bending stress may be maintained in the vanes, effecting said interference fitting engagement.

Alternatively, each shroud portion may have stepped end surfaces which are in sliding contact with those of adjacent shroud portions.

Each vane may, moreover, be integral with its shroud portion or portions.

The inner shroud may also consist of shroud portions each carried by a respective vane, each inner shroud Patented Dec. 8, 1970 portion comprising means to interlock with an adjacent shroud portion to form the inner shroud, said inner shroud supporting the vanes.

Additionally, the invention comprises a vane adapted to be assembled with a plurality of like vanes to form the said rotor, the vane having an outer and/or inner shroud portion, each said shroud portion having sloping end surfaces which are slidable over those of the adjacent shroud portions in the assembled rotor.

The vanes may be straight axially or curved and may have cooling air holes.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIG. 1 is a diagrammatic end view of one embodiment of a rotor in accordance with the present invention,

FIG. 2 is a broken away view showing part of the structure of FIG. 1 on a larger scale,

FIG. 3 is a longitudinal section taken on the line 3-3 of FIG. 1,

FIG. 4 is a view similar to FIG. 1 but illustrating a modification, and

FIG. 5 is a sectional view illustrating a different embodiment of a rotor according to the present invention.

Referring first to the embodiment of the present invention which is shown in FIGS. 1 to 3, a rotary pressure exchanger has a rotor 20 which is arranged to be driven through stub shafts 22, 23 (FIG. 3). Mounted concentrically about the axis of the rotor 20 are radially spaced apart inner and outer shrouds 24, 25 respectively.

A plurality (e.g., twenty-two) of angularly spaced apart, radially extending, vanes 26 extends between the inner shroud 24 and the outer shroud 25. The vanes 26 define with the shrouds 24, 25 a plurality of angularly spaced apart, axially extending, pressure exchanger cells 27 each of which is open at its axially opposite ends 30, 31 (FIG. 3).

Each of the vanes 26 is provided with a dove-tailed root portion 32 which is a snug fit in a correspondingly shaped recess 33 in the inner shroud 24, the latter being constituted by a single integral inner shroud member which is provided for all the vanes 26.

Each of the vanes 26 is provided at its tip with integrally formed outer shroud portions 34, the shroud portions 34 collectively constituting the outer shroud 25. Each shroud portion 34 has parts 35, 36 which are disposed on circumferentially opposite sides of the vane 26. The part 35 extends circumferentially throughout a substantially greater distance than the part 36, so that the shroud portion 34 as a whole has a centre of gravity 37 which is circumferentially offset with respect to the centre of gravity 38 of the respective vane 26.

The parts 35, 36 of each shroud portion 34 have sloping end surfaces 41, 42 respectively which are respectively slidable over and overlap the end surfaces 42, 41 of the adjacent shroud portions 34 during operation of the rotor. Thus the end surfaces 41, 42 slidingly abut each other at all times.

The vanes 26 and shroud portions 34 are assembled in such a way that, when the rotor 20 is cold, the shroud portions 34 are in interference fitting engagement with each other so as to cause the sloping end surfaces 41, 42 to be forced against each other to produce a perfect seal therebetween. As the rotor becomes hotter during operation, the seal produced by this interference fitting engagement between the shroud portions 34 may be progressively relaxed. However, by reason of the fact that the centre of gravity 37 of each shroud portion 34 is circumferentially offset with respect to the centre of gravity 38 of its vane 26, the centrifugal forces which will be operating at this time will force the sloping end surfaces 41, 42 against each other so as to maintain the 3 seal. It will be noted that the peripheral length of the shroud portions 34 is approximately the same as the radial length of the vanes 26, as shown in the drawings.

Thus the full lines in FIG. 2 show the positions of the vanes 26 and inner and outer shrouds 24, when the rotor is cold and static. The broken lines of FIG. 2, however, show the relative positions of these parts in their designed running condition.

As will be readily understood, the provision of the shroud portions 34 with the sloping end surfaces 41, 42 and the slight pivotal movement of the shroud portions 34 with respect to the vanes 26, provides accommodation for differential thermal expansion between the vanes 26 and the inner shroud 24 and outer shroud 25. Moreover, the vanes 26 themselves may flex as indicated in FIG. 2 so that the parts thereof adjacent to the outer shroud 25 may pivot with respect to the latter so as to provide yet further accommodation for such differential thermal expansion.

The relative movement which will occur between adjacent vanes 26 at the surfaces 41, 42 will also assist in damping vibrations.

Since, moreover, the surfaces 41, 42 are such as to permit relative movement therebetween, not merely will this cater for the differential thermal expansion referred to above, but also minor inaccuracies in the arc length 43 of a shroud portion 34 will be accommodated by relative sliding movement between the respective surfaces 41, 42.

The are lengths 43 are made such that a smooth continuous outer shroud 25 is obtained at the said designed running conditions, manufacturing tolerances of the arc lengths 43 being accommodated by the said sliding at the surfaces 41, 42 and/or by the fitting of shroud portions 34 which are somewhat oversize.

The vanes 26 may be sprung into a slightly curved shape to rotate the shroud portions 34 during assembly, and a slight additional springing may be required to assemble the last vane.

The vanes 26 with their root portions 32 and their shroud portions 34 may be formed integrally by forging or may be cut from long formed sections so that the rotor 20 may be relatively inexpensively manufactured. Moreover, the inner shroud 24 may be readily made of a different material from the vanes 26 and their shroud portions 34. This is desirable because it permits the vanes 26 to be made of a material which will withstand fatigue, and for the inner shroud 24 to be made of a material which withstands creep.

The surfaces 41, 42 may be hardened, e.g. by heat treatment or by plating or coating them with suitable i material.

It will be appreciated that, although there may be, in operation, a temperature gradient of several hundred degrees centigrade between opposite ends of the rotor 20, nevertheless the construction described above will cater satisfactorily for the resulting differential thermal expansions.

If desired, the vanes 26, instead of being provided with dove-tailed root portions 32 as shown, may be provided with root portions of cylindrical form. In this way, angular movement of the vanes 26 can take place by virtue of pivotal movement at the root portions rather than by bending of the vane structure.

Moreover, the sloping end surfaces 41, 42 of each shroud portion 34 may be replaced by axially extending stepped end surfaces (not shown) Which are in sliding contact with those of adjacent shroud portions 34. Thus the part 35 of each shroud portion 34 may have a single outwardly facing step which is in sliding contact with a single inwardly facing step of the part 36 of the next adjacent shroud portion 34.

In FIG. 4 there is shown a rotor 44 of a rotary pressure exchanger which is generally similar to the rotor 20 of FIGS. 1 to 3 and which for this reason will not be de- 4 scribed in detail, like parts being given the same reference numerals.

In the case of the rotor 44, however, each of the vanes 26 is integrally formed not merely with an outer shroud portion 34 but also with an inner shroud portion 45 which is disposed radially outwardly of the respective root portion 32, the inner shroud portions 45 collectivel constituting the inner shroud 24. The inner shroud portion 45 is shaped similarly to the outer shroud portion 34 and has sloping end surfaces 46, 47 which overlap and are slidable over those of the adjacent inner shroud portions 45, so that there is sliding abutment therebetween at all times so as to accommodate differential thermal expansion between the inner shroud 24 and the vanes 26.

In FIG. 5 there is shown a pressure exchanger rotor 50 having radially spaced apart inner and outer shrouds 51, 52 between which extend a plurality of angularly spaced apart, radially extending vanes 53.

Each of the vanes 53 is formed integrally with an outer shroud portion 54 and an inner shroud portion 55. The outer shroud portions 54 collectively constitute the outer shroud 52, while the inner shroud portions 55 collectively constitute the inner shroud 51.

Each of the outer shroud portions 54 is relatively thin and flexible and has an end portion 56 which is remote from the respective vane 53, and the end portion 56 constituting a tongue which is slidingly received within a groove 57 in the adjacent shroud portion 54. The tongue and groove connections 56, 57 are such as to permit relative circumferential movement between adjacent vanes 53. Thus the parts of the tongue and groove connections slidingly abut each other at all times.

Each of the inner shroud portions 55 has a flange 60 at its end remote from the respective vane 53. A radially outwardly extending recess 61 is formed in each of the flanges 60 and receives an internal flange 62 of the adjacent inner shroud portion 55. This construction mechanically interlocks the portions 55 with each other.

The vanes 53 and inner and outer shroud portions 54, 55 collectively define a plurality of angularly spaced apart, axially extending, pressure exchanger cells 63 each of which is open at its axially opposite ends.

As with the constructions of FIGS. 1 to 4, the rotor 50 is so formed as to accommodate differential thermal expansion between its vanes and its inner and outer shrouds 51, 52 since, if such expansion occurs, not merely can there be flexure in the vanes 53 and outer shroud portions 54, and hence relative pivotal movement therebetween, but also there can be some relative circumferential movement between the outer shroud portions 54.

I claim:

1. A pressure exchanger rotor having inner and outer shrouds which are radially spaced apart and a plurality of angularly spaced apart vanes extending between the shrouds to define therewith a plurality of angularly spaced apart axially extending pressure exchanger cells, each of which is open at its opposite ends; at least the outer shroud comprising a plurality of shroud portions, each of said shroud portions being integral with and carried by one of the vanes, each of said shroud portions having surfaces at its ends, which surfaces are circumferentially slidable over those of adjacent shroud portions, the shroud portions being in sliding and sealing abutment with each other at all times.

2. A pressure exchanger vane adapted to be assembled with a plurality of like vanes to form a pressure exchanger rotor, the vane having a shroud portion integral therewith, said shroud portion having sloping end surfaces which are slidable over those of adjacent shroud portions in the assembled rotor.

3. A rotor as claimed in claim 1 in which each of the vanes has a shroud portion which is connected to the adjacent shroud portions by a sliding tongue and groove connection.

4. A pressure exchanger rotor having inner and outer shrouds which are radially spaced apart and a plurality of angularly spaced apart vanes extending between the shrouds to define therewith a plurality of angularly spaced apart axially extending pressure exchanger cells, each of which is open at its opposite ends; at least the outer shroud comprising a plurality of shroud portions, each of said shroud portions being integral with and carried by one of the vanes, each of said shroud portions having sloping surfaces at its ends, which surfaces are radially and circumferentially slidable over those of adjacent shroud portions, the shroud portions being in sliding and sealing abutment with each other at all times.

5. A rotor as claimed in claim 4 in which the centre of gravity of each shroud portion is circumferentially offset with respect to that of its vane, the sloping end surfaces of adjacent shroud portions being forced against each other by centrifugal force when the rotor is rotated.

6. A rotor as claimed in claim 4 in which, when the rotor is cold, the shroud portions are in interference fitting engagement with each other.

7. A rotor as claimed in claim 3 wherein the inner shroud also consists of shroud portions each carried by a respective vane, each inner shroud portion comprising means to interlock with an adjacent shroud portion to form the inner shroud, said inner shroud supporting the vanes.

8. A rotor as claimed in claim 5 wherein the peripheral length of the outer shroud portion carried by each vane is approximately the same as the radial length of the vane.

9. A rotor as claimed in claim 4 wherein the inner shroud also consists of shroud portions which are carried by the vanes, each shroud portion having sloping surfaces at its ends, which surfaces are radially and circum ferentially slidable over those of adjacent shroud portions, the shroud portions being in sliding abutment at all times.

10. A rotor as claimed in claim 6 wherein, when the rotor is cold, a bending stress is maintained in the vanes, effecting said interference fitting engagement.

References Cited UNITED STATES PATENTS 2,772,854 12/1956 Anxionnaz 416-490 3,086,697 4/1963 Gardiner et a1. 417-64 EVERETTE A. POWELL, IR., Primary Examiner 

